1. Field
The present disclosure relates to a genetically modified microorganism that produces 4-hydroxybutyrate and a method of producing 4-hydroxybutyrate using the genetically modified microorganism.
2. Description of the Related Art
Biodegradable polymers have been suggested as an alternative to the synthetic polymers which account for a great part of severe environmental pollution. Accordingly, various biodegradable polymers have been developed. One such biodegradable polymer is poly-β-hydroxybutyrate, which is a biodegradable polymer accumulated in a nutritionally imbalanced state by various microorganisms and has excellent properties such as biodegradability, moisture resistance, piezoelectricity, and biocompatibility. 4-hydroxybutyrate (4HB), which is one of the various types of poly-β-hydroxybutyrate, is a representative polyhydroxyalkanoate (PHA). 4HB is a substance produced as a white powder in a small quantity from wine, beef, and fruit. Many studies are conducted with regard to 4HB as a biodegradable plastic material as 4HB shows a wide range of physical properties from crystalline plastic to highly elastic rubber as 4HB is similar to polyester. 4HB for medical use is generally produced by fermentation. Although a method of producing 1,4-butandiol (1,4-BDO) from 4HB is known, it has not been commercialized yet.
4HB has been used as a starting material in producing other C4-chemicals such as 1,4-BDO and γ-butyrolactone (GBL) by methods using a microorganism. 4HB may easily be converted to various other C4-chemicals such as 1,4-BDO, GBL, and tetrahydrofuran (THF). These various chemicals are used in the chemical industries as polymer, solvent, and fine chemical intermediates.
Most C4-chemicals that are currently synthesized are derived from 1,4-butandiol or maleic anhydride, but the chemical production process needs to be improved or replaced by a newly developed process as production costs are increasing due to rising oil prices. A biological process for producing C4-chemicals is suggested as an alternative to the chemical process, but the yield of 4HB production using conventional microorganisms is low. Thus, there is a need for a mutant microorganism capable of producing 4HB, and a biological method of producing 4HB using the mutant microorganism.